Page 608 - (DK) The Ultimate Visual Dictionary 2nd Ed.

the modern world
Cloning technology Spare cells from

egg development

IN A LIVING CELL THE GENETIC MATERIAL DNA (deoxyribonucleic NORMAL REPRODUCTION
acid) contains thousands of units called genes that carry Nucleus with
instructions for development, growth, and repair of the living mother’s
genetic
creature. During normal reproduction, half the mother’s genetic material
material contained in an egg cell joins with half the genetic
material from the father carried in a sperm cell, to form a
unique new genome (set of genes) for a new life. During the
early stages of embryo development, the fertilized egg divides Egg cell
into stem cells, which have the potential to become membrane Egg cell
specialized into the hundreds of cell types in a Nucleus with
body. Through therapeutic cloning, stem cells THERAPEUTIC CLONING mother’s
genetic
can be produced in a laboratory. It is hoped that material Polar body
in the future this technology can be used to grow (spare genetic
material) forms
new tissue that can be transplanted back into the Egg as part of final
donor to treat illness, without fear of rejection— cell with egg cell division
when the body recognizes a transplanted part polar body
as “foreign” because it has different genes, and Zona Fragments of DNA stain as
dark “bar code” bands
tries to destroy it. In another form of cloning, pellucida
performed experimentally using animals, genetic (outer casing
of egg cell)
material from a donor animal has been inserted
into an egg from another animal that has “Plug” of
been emptied of its own genetic zona
material, to produce an removed
animal genetically
identical to the donor.

Suction through micro­ Gentle suction GEL IMAGE SHOWING DNA
pipette holds egg steady through micro­ PROFILE
needle
Micro­needle Zona plug
inserted through egg discarded Egg cell
cell membrane provides
conditions for
Polar body Discarded multiplication
removed parts no
longer
needed
Egg genetic
material in
Zona (casing) Egg cell nucleus
removed

Donor genetic
material
introduced
Egg cell into egg cell
nucleus
containing
genetic Stem cells
material “Enucleated” egg cell (unspecialized or
(lacks nucleus with undifferentiated cells)
CENETIC MATERIAL REMOVED FROM EGG genetic material) collected from donor
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